As with capital goods (tangible items such as buildings, machinery, and equipment produced and used in the production of other goods and services), the consumption of a durable good is spread over its life span, which tends to create demand for a series of maintenance services.
The event which is referred to as The Phoenix Lights comprised of a series of incidents, involving a number of different craft and orbs which took place during the evening of March 13th 1997.
On April 21, 2008, lights were again reported over North Phoenix by local residents. According to witnesses, the lights formed a vertical line, then spread apart and made a diamond shape. The lights also formed a U-shape at one time.